Skip to main content

Wednesday, April 10, 2019

Today's Message

Posted: Wednesday, April 10, 2019

GLC Seminar: 'Varied Response of Macrobenthos to Recurring and Abated Environmental Stressors' - April 18

The Buffalo State Great Lakes Center will host the seminar "Varied Response of Macrobenthos to Recurring and Abated Environmental Stressors," presented by GLC research scientist candidate Shivakumar Shivarudrappa, on Thursday, April 18, at 12:15 p.m. in Science and Mathematics Complex 161. Please come, and encourage your students to attend.

The northern Gulf of Mexico (nGoM) contains more than 50 percent of U.S. coastal wetlands that provide innumerable ecosystem goods and services to humans. As a result of increased anthropogenic activities, nGoM is a site of the largest oil spill and hypoxic zone in the United States. Two different studies were conducted to assess the impact of these man-made environmental disasters on macrobenthos communities. Samples for the hypoxia study were collected between 2009 and 2010 from four sites with different hypoxia exposure history on the nGoM continental shelf. The Pearson and Rosenberg (P-R) model was used to assess the impact of hypoxia on the macrobenthic community. The bottom-water concentration of dissolved oxygen (DO) was used as a proxy for organic enrichment to test the underlying principles of the P-R model. The results indicated a cumulative effect of annually recurring hypoxia on the macrobenthos. High values of species diversity, richness, and evenness at the least stressed site and low values at the most stressed site indicated the existence of a westward-diminishing hypoxic gradient on the nGoM shelf interrupted by the Atchafalaya River discharge. These results were consistent with the predictions of the P-R model.

Samples for the oil spill impact study were collected between 2013 and 2016 from six different sites in the subtidal zone adjacent to the Terrebonne Bay marsh in Louisiana. The community assessment indicated that the total abundance, species richness, and Shannon diversity of macrobenthos community increased in successive years from 2013, while evenness decreased. Although the community parameters showed increasing inter-annual trends, they did not exhibit any seasonal trends. The community dominated by suspension feeding polychaetes in 2013 shifted to deposit feeding crustaceans in 2016. Assessment of ecological health status using the multivariate AZTI marine biotic index indicated improving ecological conditions from 2013 to 2016. Macrobenthos community indicated clear spatial trends to hypoxia and distinct temporal trends to oil spill stresses. Influence of environmental variables such as sedimentary organic carbon, bottom-water DO, sediment grain size, and residual hydrocarbons present in sediment and water were examined to explain variability in the benthic community structure using multivariate analyses such as SIMPER, ANOSIM, NMDS, db-RDA, CCA, and PCA.

Submitted by: Susan Dickinson